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Thread: Modding Boost Switch on Bugera V22

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    Supporting Member blearyeyes's Avatar
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    Modding Boost Switch on Bugera V22

    Boost switch sounds bad, is there a way to change the frequencies boosted?
    It inserts a 10M resistor into the tone stack. I tried to attach the relevant part of the schematic.
    Any suggestions welcome!
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    Old Timer olddawg's Avatar
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    I use one of these amps a lot. I honestly have people ask me if it is a botique amp even with stock tubes and speaker. (But mine is broken in) The "Boost" switch is simply a midrange boost. It isn't a gain boost. I honestly don't use it. This amp REALLY likes pedals. I use a Bad Monkey boost pedal and a dirt box, usually a BBE Blacksmith. With channel switching I find the amp very usable. I also use a Weber Mini Mass attenuator to take the edge off. Before modding or worrying about that switch you might want to take some serious time dialing the amp in. In the same set I will use an LP, a Strat, and an electric resonator guitar from Fender clean to Marshall grind. If the Mid Boost truly sounds "bad" you might try swapping some preamp tubes around or seeing if another V22 has the same problem, as it hasn't been my experience. It just boosts the mids.

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    Member Emeritus Forever Steve A.'s Avatar
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    Quote Originally Posted by blearyeyes View Post
    Boost switch sounds bad, is there a way to change the frequencies boosted?
    It inserts a 10M resistor into the tone stack. I tried to attach the relevant part of the schematic.
    Any suggestions welcome!
    The 10M resistor kills any switching pops. What the boost switch does is increase the value of the treble cap from 220pF to 900pF which in my opinion is too high.. (In other amps I like a 330pF treble cap and a 390pF boost cap.) You might try replacing the 680pF boost cap with 270pF or 330pF for a more subtle boost. (Actually what it does is lower the frequency of the treble control.)

    Steve Ahola

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    Quote Originally Posted by blearyeyes View Post
    Boost switch sounds bad, is there a way to change the frequencies boosted?
    It inserts a 10M resistor into the tone stack.
    The schematic is drawn incorrectly. The 10M resistor should be between 1 and 2 of the BOOST switch. As Steve says, it is used just to remove the pop when the switch is engaged. What is actually inserted into the tone stack is the 680pF capacitor. Adding it shifts mid frequencies and I'm afraid that you cannot easily change the frequencies boosted. I've seen lager capacitors in this place (up to 2.2n). What Steve explains is related to the treble boost but in this case the idea of the manufacturer was to have mid boost. Try larger capacitors but if you want to have real boost, it should be implemented differently. From my experience such a boost sounds quite good but only with high gain settings.

    Mark

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    Supporting Member blearyeyes's Avatar
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    OK got it, thanks for the explanation.

    @olddawg, yea I really like the amp and it is a BootTeak amp. Just a Chinese style of BootTeak. 8-) Think I'll take you advice and let things be.

    I haven't been around here for a while (you guys helped me fix a ValveState Marshall amp a few years back. I felt like I had run a marathon) Been building Guitar Pedals. I have a little Opto based compressor driving the V22 and it sounds great. I'll be lurking about. Getting the itch to build an amp.

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    Member Emeritus Forever Steve A.'s Avatar
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    In early Mesa Boogie amps it was called a "Shift" switch as it brought the frequency of the tone stack down somewhere between a fifth and an octave. Dumble used a larger value (.002uF) for his mid boost switch (often labelled "Deep".)

    900pf is right in the middle, neither fish nor fowl, and it should be simple enough to change the value either way. Tack on an extra 1200pf to get the Dumble value or replace it with a smaller cap to get the Mesa Boogie value.

    I haven't looked into my brand new V22 Infinium head yet to see exactly what is involved... (I certainly didn't need another guitar amp but it was 36 months same as cash and the amp is one of the best designs I have ever heard with a good and loud clean channel and an OD channel that goes from low gain overdrive to Robben Ford Zen Drive/Dumble tones.)

    Steve Ahola

    P.S. Like the Peavey C30 there is a Dumblish local feedback loop on the gain stage that feeds the tone stack... a 2M2 resistor from the .047uF coupling cap back to the grid. Although Dumble usually used a 22M resistor the drawing sold by Pat's Schematics in the 90's (remember him?) showed the 2M2 value.

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    Last edited by Steve A.; 06-01-2016 at 10:22 PM.

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    Old Timer olddawg's Avatar
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    The only thing I have found wrong with these amps is the reverb is a little bit of a compromise and the cabinet is heavier than it should be. I've seen people like them enough to make lighter cabs for them. But for $249 (on sale), free shipping, and no tax (if you look around) it's an unbelievable value. Great, versatile club amp. That mid boost switch I assume is appropriate if you plug a DS 1 and a guitar equipped with EMGs into it.

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    Member Emeritus Forever Steve A.'s Avatar
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    The V22 has an FX loop if you want something better than the basic but decent digital reverb module. There are fancier digital reverb modules... I wonder if someone will figure out (and post!) how to use them to upgrade the stock modules used in most amps these days.

    (I got the head because of the weight of the combo.)

    Steve

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    Supporting Member blearyeyes's Avatar
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    Quote Originally Posted by Steve A. View Post
    The V22 has an FX loop if you want something better than the basic but decent digital reverb module. There are fancier digital reverb modules... I wonder if someone will figure out (and post!) how to use them to upgrade the stock modules used in most amps these days.

    (I got the head because of the weight of the combo.)

    Steve
    V22 has the cool audio chip in it. I wonder if the Belton Brick is better? I have a project that uses the Belton I'll get to eventually.

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    Old Timer olddawg's Avatar
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    Quote Originally Posted by Steve A. View Post
    The V22 has an FX loop if you want something better than the basic but decent digital reverb module. There are fancier digital reverb modules... I wonder if someone will figure out (and post!) how to use them to upgrade the stock modules used in most amps these days.

    (I got the head because of the weight of the combo.)

    Steve
    The reverb is very usable. You just aren't going to get surf out of it. For me the clean channel is "close enough" to a Deluxe Reverb and the drive channel is "close enough" to an 18 watt Marshall. Mic it up and it's fine.

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    Member Emeritus Forever Steve A.'s Avatar
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    Quote Originally Posted by olddawg View Post
    The reverb is very usable. You just aren't going to get surf out of it. For me the clean channel is "close enough" to a Deluxe Reverb and the drive channel is "close enough" to an 18 watt Marshall. Mic it up and it's fine.
    My friend Felix is quite a connoisseur and he gives a thumbs up to the digital reverb in his V22. With many of the new amps the digital reverb is too soft or even worse the notes don't fade away fast enough leading to cacophony with chromatic runs. (For a thicker Ronnie Earl style reverb he'd need a pedal in the FX loop.)
    He has used a DRRI for indoor gigs for many years but likes how the V22 clean channel stays clean at full volume. And he prefers the V22 OD channel to his choice Zen Drive plugged into his DRRI. He tried a V55 for about a month but thought that the OD channel didn't sound as good so he returned it to GC for another V22. For more power for outdoor gigs he could plug the FX out into another amp rather than use his 65W Super Reverb. Or mic it as you suggest.

    Steve Ahola

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    A guy on Youtube has a series of videos culminating with a mod on the V22's reverb card to access the reverb chip's other possibilities.

    https://youtu.be/qca-4XG3Mfc

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    I was looking for a forum that was discussing the reverb on a V22 infinium. The reverb on my amp that I just bought (used) seems to work ok occasionally. Other times it goes squirrely with all kinds of weird crackling noises. Sometimes shutting the power off corrects it for a bit, sometimes not. Has anyone experienced this strange phenomenon with these amps? Is there a fix for it?

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    Quote Originally Posted by rpape2601 View Post
    I was looking for a forum that was discussing the reverb on a V22 infinium. The reverb on my amp that I just bought (used) seems to work ok occasionally. Other times it goes squirrely with all kinds of weird crackling noises. Sometimes shutting the power off corrects it for a bit, sometimes not. Has anyone experienced this strange phenomenon with these amps? Is there a fix for it?
    that's the price you pay for a crappy chinese copy of a well known american made amp,that worked beautifully and stood the test of time,same thing for all the other models.

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    Not really helpful

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    Lifetime Member Enzo's Avatar
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    You have a noisy circuit, happens to any brand or model. Not one specific thing. Have to track down the source by isolation of the symptom.

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    Education is what you're left with after you have forgotten what you have learned.

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    Old Timer olddawg's Avatar
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    I donít know... I donít use the new Infinium... but Iíve been gigging with a Bugera V22 for over 3 years. Iíve beat the crap out of it and hauled it all over the county several times a week. The only problem I had was after a couple of years I had to re-tighten some screws. Some people say you should swap out the tubes and speaker. I never have. I took the badge off and people ask me what kind of boutique amp it is all of the time. It was $249 free shipping no tax from Sweetwater at the time. Canít beat that ! My buddyís little Mesa wouldnít come on last night so I let him use it for a song until the break. With my old Rat pedal. He loved it. As for your problem... try cleaning your effects send and return jacks. Start by just plugging in a jumper cable. Truthfully.. the reverb on these isnít great. Thereís no tank. Itís a cheap digital. You arenít going to get surf out of it. If you keep it under 4 itís fine. I play next to Deluxe Reverbs, etc all of the time. Itís much more versitile imho and have had no problems with it at all. I just sold several vintage amps because I wasnít using them. Your mileage may vary of course.

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